For applications requiring a visual display of process temperatures and Settings, the 800 Series offers a height readable 4-inch setting/indicating ruler. It is available in two models: Lexan housing for Class 1 or Class 4 housing applications (with option M300), Lexan Window and epoxy-coated aluminum housing for Div. 1. Explosion-proof application. For temperature indication only, the T800 thermometer has the same performance and construction characteristics as the 800 series.